'Shinano Hope', a Fusarium root rot - Resistant lettuce

Abstract

The recent increase of root rot of lettuce (RRL) in Nagano, a major lettuce producing area in Japan, is becoming a serious problem because there are no suitable cultivars for summer cropping of crisphead-type lettuce (crisp-lettuce) resistant to RRL. We bred 'Shinano Hope' crisp-lettuce that is resistant to Fusarium oxysporum f. sp. lactucae (FOL) Race 1 that is adaptable for summer cultivation. 'Shinano Hope' is a hybrid between two crisp-lettuce lines: one is from a slow bolting selection line,whereas the other is from a breeding line resistant to FOL Race 1. 'Shinano Hope' is field-resistant to FOL Race 1, similar to its paternal plant. It's resistance is superior to those of other lettuce cultivars that can be grown in mid-summer in Nagano. The leaf color of 'Shinano Hope' is lustrous green. The leaf margins have relatively shallow incision, indentation, and mild undulation. The quality of the head in appearance upon harvest was categorized as "good-superior"; it matures similar to 'Patriot' and tends to bolt slowly in mid-summer.